ladybird/Libraries/LibWeb/CSS/Parser/MediaParsing.cpp
Sam Atkins 38aca62ef5 LibWeb/CSS: Make media-type more permissive
The current spec defines this simply as `<ident>`, but does apparently
serialize as lowercase.

Because of this change, we no longer need to care about the deprecated
media types, as they all behave the same as unknown ones.

We still keep an enum around for KnownMediaType, to avoid repeated
string comparisons when evaluating it.

Gets us 2 WPT passes.
2025-05-23 10:17:58 +01:00

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/*
* Copyright (c) 2018-2022, Andreas Kling <andreas@ladybird.org>
* Copyright (c) 2020-2021, the SerenityOS developers.
* Copyright (c) 2021-2024, Sam Atkins <sam@ladybird.org>
* Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <LibWeb/CSS/CSSMediaRule.h>
#include <LibWeb/CSS/CSSNestedDeclarations.h>
#include <LibWeb/CSS/CalculatedOr.h>
#include <LibWeb/CSS/MediaList.h>
#include <LibWeb/CSS/MediaQuery.h>
#include <LibWeb/CSS/Parser/Parser.h>
namespace Web::CSS::Parser {
Vector<NonnullRefPtr<MediaQuery>> Parser::parse_as_media_query_list()
{
return parse_a_media_query_list(m_token_stream);
}
template<typename T>
Vector<NonnullRefPtr<MediaQuery>> Parser::parse_a_media_query_list(TokenStream<T>& tokens)
{
// https://www.w3.org/TR/mediaqueries-4/#mq-list
// AD-HOC: Ignore whitespace-only queries
// to make `@media {..}` equivalent to `@media all {..}`
tokens.discard_whitespace();
if (!tokens.has_next_token())
return {};
auto comma_separated_lists = parse_a_comma_separated_list_of_component_values(tokens);
AK::Vector<NonnullRefPtr<MediaQuery>> media_queries;
for (auto& media_query_parts : comma_separated_lists) {
auto stream = TokenStream(media_query_parts);
media_queries.append(parse_media_query(stream));
}
return media_queries;
}
RefPtr<MediaQuery> Parser::parse_as_media_query()
{
// https://www.w3.org/TR/cssom-1/#parse-a-media-query
auto media_query_list = parse_as_media_query_list();
if (media_query_list.is_empty())
return MediaQuery::create_not_all();
if (media_query_list.size() == 1)
return media_query_list.first();
return nullptr;
}
// `<media-query>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-query
NonnullRefPtr<MediaQuery> Parser::parse_media_query(TokenStream<ComponentValue>& tokens)
{
// `<media-query> = <media-condition>
// | [ not | only ]? <media-type> [ and <media-condition-without-or> ]?`
// `[ not | only ]?`, Returns whether to negate the query
auto parse_initial_modifier = [](auto& tokens) -> Optional<bool> {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
auto& token = tokens.consume_a_token();
if (!token.is(Token::Type::Ident))
return {};
auto ident = token.token().ident();
if (ident.equals_ignoring_ascii_case("not"sv)) {
transaction.commit();
return true;
}
if (ident.equals_ignoring_ascii_case("only"sv)) {
transaction.commit();
return false;
}
return {};
};
auto invalid_media_query = [&]() {
// "A media query that does not match the grammar in the previous section must be replaced by `not all`
// during parsing." - https://www.w3.org/TR/mediaqueries-5/#error-handling
if constexpr (CSS_PARSER_DEBUG) {
dbgln("Invalid media query:");
tokens.dump_all_tokens();
}
return MediaQuery::create_not_all();
};
auto media_query = MediaQuery::create();
tokens.discard_whitespace();
// `<media-condition>`
if (auto media_condition = parse_media_condition(tokens)) {
tokens.discard_whitespace();
if (tokens.has_next_token())
return invalid_media_query();
media_query->m_media_condition = media_condition.release_nonnull();
return media_query;
}
// `[ not | only ]?`
if (auto modifier = parse_initial_modifier(tokens); modifier.has_value()) {
media_query->m_negated = modifier.value();
tokens.discard_whitespace();
}
// `<media-type>`
if (auto media_type = parse_media_type(tokens); media_type.has_value()) {
media_query->m_media_type = media_type.release_value();
tokens.discard_whitespace();
} else {
// https://drafts.csswg.org/mediaqueries-4/#error-handling
// A media query that does not match the grammar in the previous section must be replaced by not all during parsing.
return invalid_media_query();
}
if (!tokens.has_next_token())
return media_query;
// `[ and <media-condition-without-or> ]?`
if (auto const& maybe_and = tokens.consume_a_token(); maybe_and.is_ident("and"sv)) {
if (auto media_condition = parse_media_condition(tokens)) {
// "or" is disallowed at the top level
if (is<BooleanOrExpression>(*media_condition))
return invalid_media_query();
tokens.discard_whitespace();
if (tokens.has_next_token())
return invalid_media_query();
media_query->m_media_condition = move(media_condition);
return media_query;
}
return invalid_media_query();
}
return invalid_media_query();
}
// `<media-condition>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-condition
OwnPtr<BooleanExpression> Parser::parse_media_condition(TokenStream<ComponentValue>& tokens)
{
return parse_boolean_expression(tokens, MatchResult::Unknown, [this](TokenStream<ComponentValue>& tokens) -> OwnPtr<BooleanExpression> {
return parse_media_feature(tokens);
});
}
// `<media-feature>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-feature
OwnPtr<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& tokens)
{
// `[ <mf-plain> | <mf-boolean> | <mf-range> ]`
tokens.discard_whitespace();
// `<mf-name> = <ident>`
struct MediaFeatureName {
enum Type {
Normal,
Min,
Max
} type;
MediaFeatureID id;
};
auto parse_mf_name = [](auto& tokens, bool allow_min_max_prefix) -> Optional<MediaFeatureName> {
auto transaction = tokens.begin_transaction();
auto& token = tokens.consume_a_token();
if (token.is(Token::Type::Ident)) {
auto name = token.token().ident();
if (auto id = media_feature_id_from_string(name); id.has_value()) {
transaction.commit();
return MediaFeatureName { MediaFeatureName::Type::Normal, id.value() };
}
if (allow_min_max_prefix && (name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) || name.starts_with_bytes("max-"sv, CaseSensitivity::CaseInsensitive))) {
auto adjusted_name = name.bytes_as_string_view().substring_view(4);
if (auto id = media_feature_id_from_string(adjusted_name); id.has_value() && media_feature_type_is_range(id.value())) {
transaction.commit();
return MediaFeatureName {
name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) ? MediaFeatureName::Type::Min : MediaFeatureName::Type::Max,
id.value()
};
}
}
}
return {};
};
// `<mf-boolean> = <mf-name>`
auto parse_mf_boolean = [&](auto& tokens) -> OwnPtr<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value()) {
tokens.discard_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
return MediaFeature::boolean(maybe_name->id);
}
}
return {};
};
// `<mf-plain> = <mf-name> : <mf-value>`
auto parse_mf_plain = [&](auto& tokens) -> OwnPtr<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto maybe_name = parse_mf_name(tokens, true); maybe_name.has_value()) {
tokens.discard_whitespace();
if (tokens.consume_a_token().is(Token::Type::Colon)) {
tokens.discard_whitespace();
if (auto maybe_value = parse_media_feature_value(maybe_name->id, tokens); maybe_value.has_value()) {
tokens.discard_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
switch (maybe_name->type) {
case MediaFeatureName::Type::Normal:
return MediaFeature::plain(maybe_name->id, maybe_value.release_value());
case MediaFeatureName::Type::Min:
return MediaFeature::min(maybe_name->id, maybe_value.release_value());
case MediaFeatureName::Type::Max:
return MediaFeature::max(maybe_name->id, maybe_value.release_value());
}
VERIFY_NOT_REACHED();
}
}
}
}
return {};
};
// `<mf-lt> = '<' '='?
// <mf-gt> = '>' '='?
// <mf-eq> = '='
// <mf-comparison> = <mf-lt> | <mf-gt> | <mf-eq>`
auto parse_comparison = [](auto& tokens) -> Optional<MediaFeature::Comparison> {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
auto& first = tokens.consume_a_token();
if (first.is(Token::Type::Delim)) {
auto first_delim = first.token().delim();
if (first_delim == '=') {
transaction.commit();
return MediaFeature::Comparison::Equal;
}
if (first_delim == '<') {
auto& second = tokens.next_token();
if (second.is_delim('=')) {
tokens.discard_a_token();
transaction.commit();
return MediaFeature::Comparison::LessThanOrEqual;
}
transaction.commit();
return MediaFeature::Comparison::LessThan;
}
if (first_delim == '>') {
auto& second = tokens.next_token();
if (second.is_delim('=')) {
tokens.discard_a_token();
transaction.commit();
return MediaFeature::Comparison::GreaterThanOrEqual;
}
transaction.commit();
return MediaFeature::Comparison::GreaterThan;
}
}
return {};
};
auto flip = [](MediaFeature::Comparison comparison) {
switch (comparison) {
case MediaFeature::Comparison::Equal:
return MediaFeature::Comparison::Equal;
case MediaFeature::Comparison::LessThan:
return MediaFeature::Comparison::GreaterThan;
case MediaFeature::Comparison::LessThanOrEqual:
return MediaFeature::Comparison::GreaterThanOrEqual;
case MediaFeature::Comparison::GreaterThan:
return MediaFeature::Comparison::LessThan;
case MediaFeature::Comparison::GreaterThanOrEqual:
return MediaFeature::Comparison::LessThanOrEqual;
}
VERIFY_NOT_REACHED();
};
auto comparisons_match = [](MediaFeature::Comparison a, MediaFeature::Comparison b) -> bool {
switch (a) {
case MediaFeature::Comparison::Equal:
return b == MediaFeature::Comparison::Equal;
case MediaFeature::Comparison::LessThan:
case MediaFeature::Comparison::LessThanOrEqual:
return b == MediaFeature::Comparison::LessThan || b == MediaFeature::Comparison::LessThanOrEqual;
case MediaFeature::Comparison::GreaterThan:
case MediaFeature::Comparison::GreaterThanOrEqual:
return b == MediaFeature::Comparison::GreaterThan || b == MediaFeature::Comparison::GreaterThanOrEqual;
}
VERIFY_NOT_REACHED();
};
// `<mf-range> = <mf-name> <mf-comparison> <mf-value>
// | <mf-value> <mf-comparison> <mf-name>
// | <mf-value> <mf-lt> <mf-name> <mf-lt> <mf-value>
// | <mf-value> <mf-gt> <mf-name> <mf-gt> <mf-value>`
auto parse_mf_range = [&](auto& tokens) -> OwnPtr<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
// `<mf-name> <mf-comparison> <mf-value>`
// NOTE: We have to check for <mf-name> first, since all <mf-name>s will also parse as <mf-value>.
if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
tokens.discard_whitespace();
if (auto maybe_comparison = parse_comparison(tokens); maybe_comparison.has_value()) {
tokens.discard_whitespace();
if (auto maybe_value = parse_media_feature_value(maybe_name->id, tokens); maybe_value.has_value()) {
tokens.discard_whitespace();
if (!tokens.has_next_token() && !maybe_value->is_ident()) {
transaction.commit();
return MediaFeature::half_range(maybe_value.release_value(), flip(maybe_comparison.release_value()), maybe_name->id);
}
}
}
}
// `<mf-value> <mf-comparison> <mf-name>
// | <mf-value> <mf-lt> <mf-name> <mf-lt> <mf-value>
// | <mf-value> <mf-gt> <mf-name> <mf-gt> <mf-value>`
// NOTE: To parse the first value, we need to first find and parse the <mf-name> so we know what value types to parse.
// To allow for <mf-value> to be any number of tokens long, we scan forward until we find a comparison, and then
// treat the next non-whitespace token as the <mf-name>, which should be correct as long as they don't add a value
// type that can include a comparison in it. :^)
Optional<MediaFeatureName> maybe_name;
{
// This transaction is never committed, we just use it to rewind automatically.
auto temp_transaction = tokens.begin_transaction();
while (tokens.has_next_token() && !maybe_name.has_value()) {
if (auto maybe_comparison = parse_comparison(tokens); maybe_comparison.has_value()) {
// We found a comparison, so the next non-whitespace token should be the <mf-name>
tokens.discard_whitespace();
maybe_name = parse_mf_name(tokens, false);
break;
}
tokens.discard_a_token();
tokens.discard_whitespace();
}
}
// Now, we can parse the range properly.
if (maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
if (auto maybe_left_value = parse_media_feature_value(maybe_name->id, tokens); maybe_left_value.has_value()) {
tokens.discard_whitespace();
if (auto maybe_left_comparison = parse_comparison(tokens); maybe_left_comparison.has_value()) {
tokens.discard_whitespace();
tokens.discard_a_token(); // The <mf-name> which we already parsed above.
tokens.discard_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
return MediaFeature::half_range(maybe_left_value.release_value(), maybe_left_comparison.release_value(), maybe_name->id);
}
if (auto maybe_right_comparison = parse_comparison(tokens); maybe_right_comparison.has_value()) {
tokens.discard_whitespace();
if (auto maybe_right_value = parse_media_feature_value(maybe_name->id, tokens); maybe_right_value.has_value()) {
tokens.discard_whitespace();
// For this to be valid, the following must be true:
// - Comparisons must either both be >/>= or both be </<=.
// - Neither comparison can be `=`.
// - Neither value can be an ident.
auto left_comparison = maybe_left_comparison.release_value();
auto right_comparison = maybe_right_comparison.release_value();
if (!tokens.has_next_token()
&& comparisons_match(left_comparison, right_comparison)
&& left_comparison != MediaFeature::Comparison::Equal
&& !maybe_left_value->is_ident() && !maybe_right_value->is_ident()) {
transaction.commit();
return MediaFeature::range(maybe_left_value.release_value(), left_comparison, maybe_name->id, right_comparison, maybe_right_value.release_value());
}
}
}
}
}
}
return {};
};
if (auto maybe_mf_boolean = parse_mf_boolean(tokens))
return maybe_mf_boolean.release_nonnull();
if (auto maybe_mf_plain = parse_mf_plain(tokens))
return maybe_mf_plain.release_nonnull();
if (auto maybe_mf_range = parse_mf_range(tokens))
return maybe_mf_range.release_nonnull();
return {};
}
Optional<MediaQuery::MediaType> Parser::parse_media_type(TokenStream<ComponentValue>& tokens)
{
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
auto const& token = tokens.consume_a_token();
if (!token.is(Token::Type::Ident))
return {};
// https://drafts.csswg.org/mediaqueries-3/#error-handling
// "However, an exception is made for media types layer, not, and, only, and or. Even though they do match
// the IDENT production, they must not be treated as unknown media types, but rather trigger the malformed query clause."
if (token.is_ident("layer"sv) || token.is_ident("not"sv) || token.is_ident("and"sv) || token.is_ident("only"sv) || token.is_ident("or"sv))
return {};
transaction.commit();
auto const& ident = token.token().ident();
return MediaQuery::MediaType {
.name = ident,
.known_type = media_type_from_string(ident),
};
}
// `<mf-value>`, https://www.w3.org/TR/mediaqueries-4/#typedef-mf-value
Optional<MediaFeatureValue> Parser::parse_media_feature_value(MediaFeatureID media_feature, TokenStream<ComponentValue>& tokens)
{
// Identifiers
if (tokens.next_token().is(Token::Type::Ident)) {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
auto keyword = keyword_from_string(tokens.consume_a_token().token().ident());
if (keyword.has_value() && media_feature_accepts_keyword(media_feature, keyword.value())) {
transaction.commit();
return MediaFeatureValue(keyword.value());
}
}
// One branch for each member of the MediaFeatureValueType enum:
// Boolean (<mq-boolean> in the spec: a 1 or 0)
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Boolean)) {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto integer = parse_integer(tokens); integer.has_value()) {
if (integer.value().is_calculated() || integer->value() == 0 || integer->value() == 1) {
transaction.commit();
return MediaFeatureValue(integer.release_value());
}
}
}
// Integer
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Integer)) {
auto transaction = tokens.begin_transaction();
if (auto integer = parse_integer(tokens); integer.has_value()) {
transaction.commit();
return MediaFeatureValue(integer.release_value());
}
}
// Length
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Length)) {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto length = parse_length(tokens); length.has_value()) {
transaction.commit();
return MediaFeatureValue(length.release_value());
}
}
// Ratio
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Ratio)) {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto ratio = parse_ratio(tokens); ratio.has_value()) {
transaction.commit();
return MediaFeatureValue(ratio.release_value());
}
}
// Resolution
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Resolution)) {
auto transaction = tokens.begin_transaction();
tokens.discard_whitespace();
if (auto resolution = parse_resolution(tokens); resolution.has_value()) {
transaction.commit();
return MediaFeatureValue(resolution.release_value());
}
}
return {};
}
GC::Ptr<CSSMediaRule> Parser::convert_to_media_rule(AtRule const& rule, Nested nested)
{
auto media_query_tokens = TokenStream { rule.prelude };
auto media_query_list = parse_a_media_query_list(media_query_tokens);
auto media_list = MediaList::create(realm(), move(media_query_list));
GC::RootVector<GC::Ref<CSSRule>> child_rules { realm().heap() };
for (auto const& child : rule.child_rules_and_lists_of_declarations) {
child.visit(
[&](Rule const& rule) {
if (auto child_rule = convert_to_rule(rule, nested))
child_rules.append(*child_rule);
},
[&](Vector<Declaration> const& declarations) {
child_rules.append(CSSNestedDeclarations::create(realm(), *convert_to_style_declaration(declarations)));
});
}
auto rule_list = CSSRuleList::create(realm(), child_rules);
return CSSMediaRule::create(realm(), media_list, rule_list);
}
}